Beverage production apparatuses exist for producing frothed beverage liquids that utilize a diluent for dissolving a soluble ingredient such as coffee powder. The known systems typically utilize a mechanical high-speed rotating element such as a whipper to produce shear forces in the liquid enabling to properly dissolve the powder and produce a satisfying amount of froth.
For instance, patent applications WO 03/068039 and EP 1 639 924 relate to rotary mechanical solutions to improve frothing of liquid from a mixture of soluble ingredients and diluent.
These solutions have disadvantages in that they are noisy, involve a higher mechanical complexity and additional production costs with the need for a propelling element such as an electrical motor. Such a solution requires also more frequent cleaning or rinsing.
Therefore, these solutions using pressure prove to be not very appropriate for making a performing, low cost, noiseless and hygienic beverage producing apparatus adapted in particular for the retail channel like household small coffee appliances.
Whipperless solutions exist to provide a frothed liquid from soluble ingredient, in particular, in portioned packages such as capsules or pods. Typically, in these known solutions, a diluent is injected under pressure in a substantially closed chamber and is forced under pressure to pass through a perforated membrane or a filter to create a pressure drop and shear forces to form the frothed liquid. Although these solutions are working perfectly well, they are also complex and costly to implement because of the need to ensure a pressure tight chamber during brewing or dissolution of the ingredient. Furthermore, beverage systems using portioned packages have the disadvantage to produce packaging wastes.
For instance, WO 2005/020769 A1 relates to a method and device for the preparation of a food product by injection of a liquid through a capsule containing a food substance which is soluble and/or for extraction, whereby the liquid is injected from at least one injection point such as to generate a turbulent movement of injected liquid within the capsule thus causing brewing. As mentioned, this solution requires the capsule to be entirely filled with water until a certain pressure is built up inside the capsule in order for the diluent and beverage substance to mix together and provide a frothed beverage. Another issue is that the capsule remains full of liquid when the pressure in the capsule drops. Therefore, entire draining of the capsule is not possible.
WO 02/087400 relates to a method for preparation of a foamed drink comprising a capsule containing a foamable ingredient, providing a receptacle positioned to collect fluid escaping from the capsule, injecting liquid into the capsule to mix with the foamable ingredient, allowing the foamable ingredient mixed with the liquid to escape from the capsule into the receptacle; followed by injecting further the liquid into the receptacle in a jet having a diameter of from about 0.5 to 2 mm to produce a foamed liquid in the receptacle. However, this method has the disadvantage to require two distinct foaming steps performed respectively in the capsule and in a receptacle.
There is a need for a simpler, hygienic, and low cost solution enabling to produce a frothed liquid from the combination of a diluent and soluble ingredient or liquid concentrate and without involving the use of a pressurized chamber or motor-driven whipping means and without providing solid residues.